Effect pigments based on artificially produced substrates with a narrow size distribution

Abstract

The invention relates to effect pigments comprising artificial platelet-shaped substrates which have at least one optically active coating, where the effect pigments have a volume-averaged cumulative undersize distribution curve with the characteristic numbers D10, D50 and D90, said cumulative undersize distribution curve having a span ΔD of 0.7-1.4, and the span ΔD being calculated in accordance with formula (I):ΔD=(D90−D10)/D50  (I),and the average thickness of the artificial platelet-shaped substrates being 500 nm to 2000 nm.

What is claimed is: 
     
       1. Effect pigments consisting essentially of artificial platelet-shaped substrates which have only one optically active coating comprising TiO 2  in the rutile or anatase crystal polymorph, wherein in case of the rutile polymorph, the coating is obtained by a process comprising applying SnO 2  to the substrates, applying TiO 2  to the applied SnO 2 , and then calcining the substrates, wherein the effect pigments have a volume-averaged cumulative undersize distribution curve with the characteristic numbers D 10 , D 50  and D 90 , said cumulative undersize distribution curve having a span ΔD of 0.7-1.4, and the span ΔD being calculated in accordance with formula (I):
   Δ D =( D   90   −D   10 )/ D   50   (I),
 
 
       and the average thickness of the artificial platelet-shaped substrates being 500 nm to 2000 nm, wherein the standard deviation of the thickness of the artificial platelet-shaped substrates is 15% to 100%, and wherein the artificial platelet-shaped substrates are substantially transparent and are selected from the group consisting of glass platelets, platelets of synthetic mica, SiO 2  platelets, platelet-shaped bismuth oxychloride, platelet-shaped aluminum oxides, and mixtures thereof. 
     
     
       2. The effect pigments of  claim 1 , wherein the average thickness of the artificial platelet-shaped substrates is 750 nm to 1500 nm. 
     
     
       3. The effect pigments of  claim 1 , wherein the one optically active coating of the artificial substrates has a refractive index of n≥1.9. 
     
     
       4. Effect pigments consisting essentially of glass platelet-shaped substrates which have only one optically active coating comprising TiO 2  in the rutile or anatase crystal polymorph, wherein in case of the rutile polymorph, the coating is obtained by a process comprising applying SnO 2  to the substrates, applying TiO 2  to the applied SnO 2 , and then calcining the substrates, wherein the effect pigments have a volume-averaged cumulative undersize distribution curve with the characteristic numbers D 10 , D 50  and D 90 , said cumulative undersize distribution curve having a span ΔD of 0.7-1.4, and the span ΔD being calculated in accordance with formula (I):
   Δ D =( D   90   −D   10 )/ D   50   (I),
 
 
       and the average thickness of the platelet-shaped substrates being 500 nm to 2000 nm. 
     
     
       5. The effect pigments of  claim 4 , wherein the average thickness of the artificial platelet-shaped substrates is 750 nm to 1500 nm. 
     
     
       6. The effect pigments of  claim 4 , wherein the standard deviation of the thickness of the artificial substrates is 15% to 100%. 
     
     
       7. The effect pigments of  claim 4 , wherein the one optically active coating of the artificial substrates has a refractive index of n≥1.9. 
     
     
       8. The effect pigments of  claim 4 , wherein the average thickness of the artificial platelet-shaped substrates is 750 nm to 1500 nm and the standard deviation of the thickness of the artificial substrates is 20% to 70%. 
     
     
       9. The effect pigments of  claim 4 , wherein the average thickness of the artificial platelet-shaped substrates is 750 nm to 1500 nm the span ΔD is within a range of 0.8 to 1.2. 
     
     
       10. The effect pigments of  claim 1 , wherein the standard deviation of the thickness of the artificial platelet-shaped substrates is in a range of 15% to 70%. 
     
     
       11. The effect pigments of  claim 1 , wherein the standard deviation of the thickness of the artificial platelet-shaped substrates is in a range of 20% to 70%. 
     
     
       12. The effect pigments of  claim 1 , wherein the standard deviation of the thickness of the artificial platelet-shaped substrates is in a range of 15% to 70%, and wherein the average thickness of the substrate is 750 nm to 1500 nm. 
     
     
       13. The effect pigments of  claim 1 , wherein the standard deviation of the thickness of the artificial platelet-shaped substrates is in a range of 20% to 70%, and wherein the average thickness of the substrate is 750 nm to 1500 nm. 
     
     
       14. The effect pigments of  claim 4 , wherein the average thickness of the artificial platelet-shaped substrates is 750 nm to 1500 nm, and wherein the standard deviation of the thickness of the artificial substrates is 15% to 70%.